1. Field of the Invention
The present disclosure relates to a lock device for a vehicle retractable seat whose seat back is able to be secured to and released from a vehicle body selectively. In particular, this technology relates to a locking mechanism for locking between a member connected to a vehicle body and a member connected to a seat back when a dynamic force, which is greater than a holding force by a latch mechanism in ordinary use by user, is inputted to the vehicle body.
2. Description of Related Art
A vehicle seat attachment latch assembly is disclosed in, for example, U.S. Pat. No. 6,945,585. This latch assembly includes a latch mounted for movement between latched and unlatched positions with respect to a striker to secure and selectively release a vehicle seat with respect to a vehicle body. A latching wedge is mounted on the latch for movement therewith and for movement with respect thereto in cooperation with a bias provided by a first spring that moves a wedging surface of the latching wedge into wedging contact with the striker with the latch in its latched position in order to provide a rattle free attachment. A locking pawl and a spring cooperate to hold the latch in its latched position or permit release thereof for movement to the unlatched position where the striker is released. That is to say, the latch (member) engages with locking pawl every time when the latch member latches or holds the striker, in ordinary use by user.
As described above, according to the latch assembly in U.S. Pat. No. 6,945,585, to eliminate play between the latch member and the striker which causes a rattle, has an additional latching wedge and the bias (spring) on the latch member, for purpose of holding the striker being tightly with the latch member when the striker is positioned at a latched position. Thus, this structure requires additional members, to add a locking function/mechanism into a latching function/mechanism.
Meanwhile, U.S. Pat. No. 5,730,480 discloses a lock device for a retractable automotive seat that includes a base member having a striker receiving slot into which the striker can be led. A latch plate is pivotally connected to the base member. A locking plate is pivotally connected to the base member. A striker restraining member is pivotally connected through a pivot shaft to the base member. The striker restraining member is pivotal between a restraining position, where a contact edge thereof abuts against the striker, and a releasing position, where the contact edge disengages from the striker. Springs are employed for biasing the latch plate to pivot toward a stand-by position, biasing the locking plate to pivot toward a lock position, and biasing the striker restraining member to pivot toward the restraining position. A link mechanism is employed for causing the striker restraining member to take the restraining position when the latch plate and the locking plate take latching and lock positions respectively. The pivot shaft of the striker restraining member is positioned at the back of the striker receiving slot, so that the contact edge of the striker restraining member can abut against a front side of the striker. In other words, a locking mechanism including the locking plate, the latch plate and so forth is sandwiched by the base member and another plate.
As described above, according to the lock device in U.S. Pat. No. 5,730,480, as in FIG. 2 two plate members sandwich a locking structure/mechanism such as the locking plate, the latch plate and so forth.